For example, in a field of automobile application, in order to reduce costs, a battery with a low output voltage (for example, 3V) is expected to be used. A power supply circuit of an engine control unit (ECU) of a current vehicle has only a step-down power supply having a step-down function from a voltage of a battery to a low voltage. Therefore, a step-up/down power supply having both a step-down function and a step-up function needs to be applied to the ECU.
As a power supply which is not used for the ECU but has both a step-down function and a step-up function, for example, there is PTL 1.